Simple. Name a song that would be a hit no matter when its released in the future.

Mine Are:

Aaliyah- Try Again
Beyonce- Crazy In Love
Jay-Z- Empire State of Mind

Go.

Toxic - Britney Spears
Umbrella - Rihanna
Tik Tok - Ke$ha

Vision of Love.

NASTY!

Any Man of Mine.

Thriller.

Billie jean.
Let it Be
Smells like teen spirit
Like A Prayer
We Belong Together
Sweet Dreams (Are Made of This)
Like a virgin
Thriller
I will always love you

Firework tbh.

Baby One More Time.

I feel like the term "timeless" carries with it some sense of classiness, or elegance. So little of pop music is either classy or elegant. That's not a condemnation of the genre. I love pop for its disposable nature.

Micheal Jackson- "Billie Jean"
R. Kelly- "I Believe I Can Fly"
Beyonce- "Single Ladies"
Whitney Houston- "I Will Always Love You"
Marian Carey- "Hero"
Prince- Purple Rain

Bohemian Rhapsody
Bad Romance
Ziggy Stardust
No Woman No Cry
Over The Rainbow
Purple Rain

I Believe I Can Fly

Toxic.

Since U Been Gone -Kelly Clarkson
Irreplacable-Beyonce
Im with You-avril lavaigne
The whole 21 album

Firework
Irreplaceable

John Lennon-Imagine
Led Zeppelin-Stairway to Heaven
Ben E. King-Stand By Me
The Eagles-Hotel California
Van Morrison-Brown Eyed Girl

I had a playlist called "Timeless Classics" so this was easy

I'd also add a few pop songs from the last decade or so: Rolling In The Deep, Bad Romance, Hey Ya